Children with insomnia and shorter sleep duration had impaired modulation of heart rhythm during sleep, Pennsylvania researchers reported at the American Heart Association's 50th Annual Conference on Cardiovascular Disease Epidemiology and Prevention.
In a study of young children, researchers showed that insomnia symptoms were consistently associated with impaired heart variability measures. They also found a significant but less consistent pattern with shortened sleep duration and decreased heart rate variability.
Heart rate variability is the beat-to-beat variations of heart rate. In a healthy person, beat-to-beat intervals change slightly in response to automatic functions like breathing.
The study included 612 elementary school children in the first to fifth grades. The children were average age 9, and 25 percent were non-white and 49 percent were boys. All were generally in good health. Their parents completed the Pediatric Behavior Scale, including two questions that focused on symptoms of insomnia.
Researchers examined the children overnight in a sleep laboratory with polysomnography (PSG), a standardized method for measuring sleep disorders. The researchers measured sleep duration, trouble falling asleep, the number of wake-ups and problems going back to sleep if awakened. They also measured cardiac autonomic modulation (CAM), the balance of the sympathetic and the parasympathetic control of the heart rate rhythm.
A balance is needed between the sympathetic modulation that "excites" the heart and the parasympathetic modulation that "calms" the heart, said Mr. Fan He, the lead-author of the study and a graduate student at Penn State University College of Medicine in Hershey, Pa. "The balance between the sympathetic and the parasympathetic provides a favorable profile for the heart."
The study showed:
- Children with reported insomnia had impaired CAM with a shift towards more sympathetic or excitable activation of the heart rhythm. There was a 3 percent to 5 percent reduction in the parasympathetic modulation of heart rhythm in children with insomnia.
- Children with longer sleep duration had a slower heart rate indicative of a balance of heart rhythm, with a shift towards more parasympathetic modulation. The heart rate of children who slept eight hours was two beats per minute slower than that of kids who slept only seven hours.
- Insomnia and short sleep duration, even in young children, resulted in a physiological activation of the sympathetic modulation.
"Kids who sleep a longer duration have a healthier heart regulation profile compared to kids who sleep shorter durations," said Duanping Liao, M.D., Ph.D., co-author of the study and professor of epidemiology at Penn State University College of Medicine in Hershey, Pa. "Their hearts are more excitable if they have insomnia. If the heart is too excited, that means it is beating too fast and usually that isn't good. These data indicate that among young children with insomnia symptoms reported by their parents, there already is an impairment of cardiovascular autonomic regulation, long before they reach the traditional high-risk period for cardiovascular disease."
Parents should encourage their children to have healthy bedtime habits that encourage sleep, Liao said. "Watching television before going to bed and waking up to return text messages are examples of activities that could have a harmful affect on healthy sleep patterns in children."
Liao called for further studies in children to determine the impact of sleep deprivation and stress and the possible long-term risk of cardiovascular disease and obesity. "Previous studies have shown a strong association of heart rhythm regulation and heart risk in adults. It's quite possible that this kind of stress can have a long-term impact even at a young age."
The study was funded by the National Heart, Lung, and Blood Institute.
Other co-authors are: Xian Li, M.D., M.S.; Sol Rodriguez-Colon, M.S.; Alexandros N. Vgontzas, M.D.; Chuntao Wu, M.D., Ph.D.; and Edward O. Bixler, Ph.D. Author disclosures are on the abstract.
Contact information: Dr. Liao can be reached at (717) 531-4149 and dliao@psu.edu. Fan He can be reached at (717)-531-1172 and fhe@hes.hmc.psu.edu. (Please do not publish contact information.)
(Note: Actual presentation time is 5 p.m. PT/8 p.m. ET, Wednesday, March 3, 2010.)
Click here to download audio clips offering perspective on this research from American Heart Association spokesperson, Stephen Daniels, M.D., Ph.D., Chairman, Dept. of Pediatrics at Univ. of Colorado, Denver; Pediatrician-in-Chief & L. Joseph Butterfield Chair, The Children's Hospital.
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Abstract P09 – Reduced sleep linked to propensity to overeat
A lack of sleep can lead to an emotional state with greater susceptibility to food stimuli — and thus overeating — than regular sleep, researchers from Columbia University in New York City reported at the American Heart Association's 2010 Conference on Nutrition, Physical Activity and Metabolism.
Researchers examined the neural response to food stimuli during periods of short sleep and regular sleep. Eleven healthy, normal-weight young adults were randomized to one of two sleep duration sequences for six days (either four or nine hours of sleep), separated by a four-week washout.
Researchers performed functional magnetic resonance to measure brain activity in response to food stimuli on the last day of each phase in the fasted state. Participants were given stimuli of both food and nonfood items.
During the short sleep phase, food but not nonfood stimuli led to significant brain activity in areas such as the hypothalamus, amygdale, hippocampus and insula, researchers said. In contrast, there was little brain activity in response to food, but not nonfood stimuli during the regular sleep phase.
The hypothalamus plays a role in both sleep-wake cycles and modification of food intake. The amygdale, hippocampus and insula are emotional and motivational regions of the brain that can regulate feeding behavior.
The results showing greater activity in the brain regions associated with food intake regulation as well as emotion and motivation suggest that short sleep duration can lead to an emotional state with greater susceptibility to food stimuli than occur with a regular night's sleep, the researchers reported. "This novel neuronal link between food stimuli and sleep duration supports the notion that reduced sleep may lead to a greater propensity to overeat," researchers said.
Contact information: Marie-Pierre St-Onge, Ph.D., can be reached at (212) 523-3564 and ms2554@columbia.edu. Author disclosures are on the abstract.
(Note: actual presentation time is 5 p.m. PT/8 p.m. ET, Tuesday, March 2, 2010.)
Click here to download audio clips offering perspective on this research from American Heart Association spokesperson, Stephen Daniels, M.D., Ph.D., Chairman, Dept. of Pediatrics at Univ. of Colorado, Denver; Pediatrician-in-Chief & L. Joseph Butterfield Chair, The Children's Hospital.
Abstract P10 – Lack of sleep linked to hormone profile that increases appetite
Missing a full night's sleep can lead to a hormonal profile that results in greater food intake compared to the profile of people who sleep a sound nine hours per night, researchers reported at the American Heart Association's 2010 Conference on Nutrition, Physical Activity and Metabolism.
Normal-weight men and women, who usually slept seven to nine hours nightly, spent two six-day inpatient days where they either slept four or nine hours. The two phases of the study were separated by one month. Daily fasting blood samples were drawn from 10 subjects on days two through five.
During the short sleep cycle, subjects had significantly higher levels of fasting ghrelin, stimulating the appetite, and fasting adiponectin, a protein produced by fat cells that makes the body more sensitive to insulin. However, the subjects had a lower fasting peptide YY levels than when they were allowed to have a full night's sleep. Peptide YY is a protein released by the gut in response to feeding that lowers appetite.
"This data supports the notion that short sleep duration can lead to a hormonal profile that predisposes one to greater food intake than occurs with habitual sleep duration," the researchers said.
Contact information: Marie-Pierre St-Onge, Ph.D., can be reached at (212) 523-3564 and ms2554@columbia.edu. Author disclosures are on the abstract.
(Note: actual presentation time is 5 p.m. PT/8 p.m. ET, Tuesday, March 2, 2010.)
Click here to download audio clips offering perspective on this research from American Heart Association spokesperson, Stephen Daniels, M.D., Ph.D., Chairman, Dept. of Pediatrics at Univ. of Colorado, Denver; Pediatrician-in-Chief & L. Joseph Butterfield Chair, The Children's Hospital.
Statements and conclusions of study authors that are presented at American Heart Association scientific meetings are solely those of the study authors and do not necessarily reflect association policy or position. The association makes no representation or warranty as to their accuracy or reliability. The association receives funding primarily from individuals; foundations and corporations (including pharmaceutical, device manufacturers and other companies) also make donations and fund specific association programs and events. The association has strict policies to prevent these relationships from influencing science content. Revenues from pharmaceutical and device corporations are available at www.americanheart.org/corporatefunding.